The present invention relates, in general, to the field of magnetic recording heads for computer mass storage devices. More particularly, the present invention relates to a multi-step stud design, and method of especial utility for producing closely packed interconnects in magnetic recording heads.
Current thin film magnetic tape recording heads consist of many channels that are closely packed together on a single head. Each channel consists of a xe2x80x9creaderxe2x80x9d element and a xe2x80x9cwriterxe2x80x9d element merged on top of each other or interleaved. Each reader and writer requires a minimum of one pair of interconnect leads to the drive channel electronics, although in certain applications, several devices may share common leads such as in single-ended write heads having a common ground. At the end of each lead there is typically a stud that is plated up to a height that allows encapsulation of the head followed by planarization of the wafer topography (i.e. by lapping) which exposes the studs through the top of the insulating encapsulation material, followed by a wire bonding operation.
As the demand for higher track densities increases, the number of channels per head and channel densities likewise increases. This necessitates the fabrication of high density interconnects with high integrity. Conventional stud fabrication techniques have inherent limitations in density because of the aspect ratios required in photolithography for the fabrication of the studs. Also, current stud structures produce sufficient shadowing during the encapsulation deposition process such that there are potential chipping and reliability problems with the encapsulation surrounding the stud following lapping of the structure to the final stud height. Therefore, in order to achieve higher densities, improved uniformity of plated stud height and acceptable coverage with encapsulation are required to produce sufficiently high yields.
Studs on disk drive heads are generally larger and spaced further apart than on tape heads, since there are usually only four pads per slider. In contrast, multi-channel tape heads presently require many more pads and have interconnects that spread out from the transducers to the pads.
The multi-step stud design and method for use with closely packed interconnects in magnetic recording heads of the present invention enables more channels to be fabricated per head and allows for the provision of higher density interconnects saving considerably in wafer area. These factors, together with an improved stud shape, increases yield during fabrication while improving the long term reliability of the head.
Particularly disclosed herein is an interconnect stud structure in a magnetic recording head of a computer mass storage device which comprises a first metal layer having a first width thereof, the first metal layer being electrically coupled to at least one element (such as channel, ground or other structure) of the recording head. A second metal layer overlies the first metal layer and has a second differing width, with the second metal layer presenting an upper portion thereof for providing an electrical contact to the first metal layer. An encapsulating layer surrounds the first and second metal layers with the upper surface of the second metal layer exposed and available to permit electrical connection to the recording head.
Also particularly disclosed herein is a process for fabricating an electrical interconnect in a magnetic recording head which comprises the steps of: producing a first metal layer having a first width in electrical contact with at least one element (such as channel, ground or other structure) of the magnetic recording head; further producing a second metal layer having a second width overlying the first metal layer; encapsulating side portions of the first and second metal layers such that the encapsulation boundaries between neighboring studs do not intersect; and an upper surface of the second metal layer provides an electrical contact to the recording head.